Yam, Taro and Sweet Potato

In one of the documents I translated recently, there was a prescription drug claimed to be made from natural extract of "dioscorea spp". I looked up the term, and found it to be the scientific name of yam. True yam, that is. But the picture in the document looks like sweet potato to me, no matter how many times I blinked my eyes or applied Eye-Mo.

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Dioscorea is commonly known as "yam", or "true yam". The Chinese name is "山药". The Chinese variety is thin and long, with thin brown skin and snow-white flesh. It grows to be very long (what I can find in the local market are all over three feet long). What you see in the picture below is only half of the thing.

Yam (山药)

But what a Malaysian Chinese (or a Malaysian in general) calls "yam", is actually "taro" (芋头). The scientific name is "Colocasia esculenta".

And if you mention "yam" to a clueless American, he/she will think you are talking about "sweet potato" (番薯/甘薯, Ipomoea batatas).

Talk about confused identity. =.=